docs: def derive_rad39_corr(self, bt11, bt13, method='rosenfeld'):
          """Derive the 3.9 radiance correction factor to account for the
          attenuation of the emitted 3.9 radiance by CO2
          absorption. Requires the 11 micron window band and the 13.4
          CO2 absorption band, as e.g. available on SEVIRI. Currently
          only supports the Rosenfeld method
          """
  
          if method != 'rosenfeld':
              raise AttributeError("Only CO2 correction for SEVIRI using "
                                   "the Rosenfeld equation is supported!")
  
          LOG.debug("Derive the 3.9 micron radiance CO2 correction coefficent")
          self._rad3x_correction = (bt11 - 0.25 * (bt11 - bt13)) ** 4 / bt11 ** 4